1. Field of the Invention
The present invention relates to an expansive material for concrete used in the civil engineering and construction fields, and its preparation process.
2. Description of the Prior Art
Some proposals have been offered of a concrete expansive material capable of developing good expansion capability in small amounts (Patent Publication 1), and an expansive material for cement in which the surface of quicklime is coated with calcium carbonate (Patent Publication 2). It has also been proposed to carbonate the surface of soft burnt slaked or hydrated lime for use as a pulverizing material for set cement concrete (Patent Publication 3).
In the steel field, there has been a lime carbonation technique proposed for the purpose of holding back the hygroscopicity of lime used as a desulfurization agent.